The present invention relates to a pressure control device for an irrigation nozzle and more particularly to an irrigation sprinkler having a rotatable riser and a nonrotatable valve for regulating the flow and pressure of water through the sprinkler.
A number of sprinkler systems have been devised to provide proper irrigation to lawns and other seeded areas. Irrigation sprinklers may be generally classified as either fixed discharge or moving discharge sprinklers. A moving discharge sprinkler is characterized by a movable sprayhead which directs one or more water streams outwardly from the head of the sprinkler in a predetermined direction in a cyclic or oscillatory pattern to sweep over the area to be irrigated.
Moving discharge sprinklers have the advantage of low precipitation rates. They further have the ability to distribute a relatively small flow of water over a relatively large area. However, such moving sprinklers tend to be complex in construction, costly to manufacture, subject to wear and malfunction and sensitive to water flow rates and pressures. The coverage of these sprinklers is adversely affected by the wind and they are ill-suited to small and/or irregularly shaped areas. They are generally incapable of accurate trimming, that is, spraying along but not appreciably beyond the border of an irrigation area, particularly an irregular body. Accordingly, moving sprinklers are not satisfactory for all uses. In view of their necessity to rotate or oscillate, a relatively large area of movement is required.
Typical fixed discharge sprinkler systems normally have a stationary sprayhead which directs a number of discreet diverging streams of water or a generally continuous fan-shaped spray of water spreading outwardly from the spray head over a predetermined angular sweep. Fixed discharge sprinklers have the advantages of maximum simplicity, low cost, reliability, immunity to wear and the ability to irrigate small or irregular areas and to accurately trim the borders of such areas. The chief disadvantage of fixed discharge sprinklers is that they continuously deliver a relatively large flow of water to a relatively small area and thus produce a relatively high precipitation rate over the area. They are relatively inflexible with respect to varying the precipitation rate.
The problem of the characteristically inflexible operation of fixed discharge sprinklers is further compounded by the fact that they are usually operated in groups from a common control valve. These control valves are usually controlled or operated by a single manual or automatic controller which causes all of the sprinklers to deliver approximately the same amount of water to the areas surrounding the respective sprinklers. Thus, some areas which require less water are overwatered, while other areas requiring more water are underwatered.
Various prior art devices have attempted to eliminate these disadvantages of fixed discharge irrigation sprinkler heads. One particularly noteworthy device is disclosed in my prior U.S. Pat. No. 3,454,225 and assigned to the assignee of the present invention. The sprinkler disclosed in my prior patent calls for a plurality of triangularly-shaped discharge orifices and means for adjusting the spacing between the apices and base sides of the orifice to regulate the geometric shape of the spray pattern. The actual size of the nozzle orifice of this sprinkler may be adjusted by turning a center screw in the sprinkler. The radius of throw and volume of water discharged by the sprinkler can thereby be varied over a wide range.
Summary of the Invention
The present invention relates to an improvement of the sprinkler in my prior U.S. Pat. No. 3,454,225 to provide flow adjustment thereto. To attain this, the present invention provides for a rotatable hollow riser in the sprinkler having an inlet orifice of a predetermined shape and discharge orifice. Non-rotatable valve means is provided for regulating the flow and pressure of water through the sprinkler.
In one embodiment, the riser is sealed at the water inlet end by a suitable plug and a valve ring is snug-fit on the riser. The valve ring is keyed to a filter screen surrounding the riser to remain circumferentially stationary. The valve ring has an orifice which is congruent to the inlet orifice in the riser. The pressure to the entire sprinkler system is adjusted by rotating the riser either manually or by any suitable means. This provides for adjustment of the flow of water through the orifice in the valve ring and then through the inlet orifice in the riser.
In an alternative embodiment, a valve disc is secured to the inlet end of the riser and is circumferentially stationary with respect to the riser. The riser has a plug fixedly mounted at the inlet end and a key or splined stop on the surrounding filter keys the plug and riser to permit limited rotation. Both the valve disc and the riser have orifices which are congruent. Rotation of the riser with respect to the stationary valve disc regulate the flow of water through the valve orifice and the riser to thereby regulate the flow of water through the sprinkler.
In the operation of the present invention, the riser pops up in response to water pressure applied to the sprinkler system to discharge a fluid through the discharge orifices. The relative position of the riser with respect to the valve means provides flow adjustment through the hollow riser. The versatility of the system is thereby increased.
Accordingly, an object of the present invention is to provide a pop-up sprinkler head having flow adjustment means.
Another object is to provide means for adjusting the flow of water through the riser of a sprinkler system.
Still another object is to provide stationary valve means for a sprinkler system to adjust the volume or pressure of fluid through the system.
Yet another object is to provide a vastly improved bubbler head for an irrigation system to replace both the stream and gusher type bubblers.
A more complete and thorough understanding of the improvements of the pressure control mechanism of the sprinkler of the present invention will be afforded to those skilled in the art from a consideration of the following detailed explanation of the preferred embodiment of the invention, when considered in conjunction with the accompanying drawings.